1. Field of the Invention
The present invention relates to a mold and method for molding a metallic product capable of easily controlling the temperature of a molten metal during and after the filling of the molten metal into a cavity.
2. Description of the Related Art
There is a prior art disclosed in Japanese Unexamined Patent Publication No. 2001-18229 entitled “Mold for Molding Synthetic resin and Device and Method for Controlling Mold Temperature”. In this prior art, to easily switching the heating and the cooling of a cavity surface of the mold, a liner having a flow path is provided in a mold base, so that a hot medium is made to flow in the flow path when the molten resin is injected, on one hand, and a coolant is made to flow in the flow path thereafter to solidify a product molded within the mold, on the other hand.
When the material to be molded is synthetic resin, as an environment in which the resin is not solidified can be maintained at a temperature in a range from 200 to 250° C., it is possible to increase and reduce the mold temperature in a relatively short time. However, when the material is a metal or a metallic alloy such as magnesium alloy having a high melting point of approximately 600° C., it is necessary to increase the mold temperature to 600° C. or higher for the purpose of maintaining the molten state of the material. To do so, a long time such as, for example, from 30 minutes to 1 hour is required even if a powerful heater is used.
Also, when the temperature is reduced to approximately 300° C. at which the release of a molded product from the mold is possible after the molten magnesium alloy has been filled in the mold and solidified, a long time is necessary to increase the temperature to prepare for the next operation. Thus, when the metal is molded, it is very difficult to repeat the heating and cooling in a short time, whereby the above-mentioned prior art is not practically applicable to the production of metallic molded products.